Improvement of densification and mechanical properties of MgAl₂O₄-CaAl₄O₇-CaAl₁₂O₁₉ composite by addition of MnO

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• 作者：Xue-liang Yin^a ; ^b ; Min Chen^a ; ^{chenm@smm.neu.edu.cn} ; Nan Wang^a ; Lei Xu^a
• 关键词：MnO ; Spinel ; Calcium hexaluminate ; Densification ; Mechanical properties
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：1 April 2017
• 年：2017
• 卷：43
• 期：5
• 页码：4706-4711
• 全文大小：1784 K
• 卷排序：43

文摘

Composites containing spinel (MgAl2O4) and calcium hexaluminate (CaAl12O19) can excellently combine the properties of these two phases. However, their fabrication in dense composites for structural applications is limited on account of the poor sinterability. Considering this aspect, the effect of MnO addition on the sintering, microstructure and mechanical properties of MgAl2O4-CaAl4O7-CaAl12O19 composite was investigated by solid state reaction sintering at 1500–1600 °C. The results showed that the grain growth of MA was significantly promoted due to the formation of Mg(Mn)Al2O4 by introducing MnO. The addition of MnO can also weaken the barrier effect of the elongated CA6 grains, indirectly promoting the development of MA and CA2 grains. Accordingly, highly uniform and dense microstructures were formed, with the apparent porosity decreased from 18.3% to 3.4% when adding 6 wt% MnO at 1600 °C. Significant improvements in the mechanical properties were also achieved for the MnO added composites sintered at this temperature. The optimum flexural strength was obtained by adding 6 wt% MnO, achieving an increase from 186 to 308 MPa, while the optimum fracture toughness was obtained by adding 4 wt% MnO, with the value increased from 2.3 to 3.5 MPa m1/2.